import std.algorithm;
import std.array;
import std.ascii;
import std.container;
import std.conv;
import std.math;
import std.numeric;
import std.range;
import std.stdio;
import std.string;
import std.typecons;

void log(A...)(A arg) {
    stderr.writeln(arg);
}
int size(T)(in T s) {
    return cast(int)s.length;
}

void main() {
    auto p = [2,3,5,7,11,13];
    auto c = [4,6,8,9,10,12];
    real x = reduce!"a + b"(0, p) / cast(double)p.length;
    real y = reduce!"a + b"(0, c) / cast(double)c.length;
    int P, C; readf("%d %d\n", &P, &C);
    writefln("%.12f", (x ^^ P) * (y ^^ C));

}